Active and passive electronic components are known to be very sensitive to electrical overstress. It is therefore important for electrical soldering irons, which make frequent contact with such components, to be totally free of static and dynamic electrical potentials.
The tip and all externally exposed metal parts of a typical laboratory grade soldering iron are therefore grounded. The low ohmic grounding connection is usually made through the "green wire" of the Power Cord. However, repeated flexing of the Power Cord during soldering operations may cause the conductors In the Power Cord to break. A break in one or both of the heating current carrying conductors is immediately obvious because the soldering iron will no longer produce heat. A break in the "green grounding wire", however, is usually not readily noticed, and can thus exist for a long period of time.
When the grounding connection is no longer functional, electrical potentials of sufficient amplitude to cause latent or permanent damage may develop on the soldering iron tip. The potentials may be due either to the accumulation of Electrostatic Charge or to the coupling of alternating voltage potentials through parasitic capacitors between the heating element of the soldering iron and exposed metal on the soldering iron.
The circuit and device of the present invention allow for ongoing monitoring of the integrity of the grounding connection of the soldering Iron tip. The present invention exploits the fact that a soldering iron tip is frequently cleaned by wiping on a suitable leaning device.
The most widely used cleaning device is a moist sponge. A moist sponge usually is conductive because the water in it is highly contaminated with ionic compounds which naturally exist in the sponge and with deposits of ionic compounds that are typically found in soldering fluxes and which are deposited on the sponge during the wiping action. An electrical circuit can thus be established which comprises the soldering iron tip, the conductive sponge, and the safety ground.
Other cleaning devices use metallic sponges that are similar to steel wool but that are made out of a copper or bronze wire mesh. These sponges too are conductive, and thus can be made part of an electrical circuit as described above.
The cleaning device, whether natural or synthetic sponge or wire mesh, can be an integral part of a soldering station or it can be a stand-alone device.
Accordingly, it is an object of the present invention to provide a means to detect grounding problems in soldering irons that are in use.
It is a further object of the present invention to provide a method of monitoring the grounding connection that makes use of commonly used equipment.
It is a still further object of the present invention to provide a way to continuously monitor the grounding connection of the soldering iron.